You can't have too many ideas or too much bench. Mine, 8' of bench, it looks like I have lots of room, right? You should see it now with two progressives, two single stations, a bench primer, and a bench swager. I would be happier with twice that now, but there's a door to storage rooms on either end. Punt.
I used a torsion beam bench support (link below), Such a design saves a lot of cost and material without sacrificing strength. Triple 2x4 beam is ample at 36" high, but if you decide to build a higher bench you could even exchange the 3-2x4 beam for a 3-2x6 one.....
https://www.ar15.com/forums/topic.html?b=6&f=42&t=319362
Not shown is the Thumbers, the Lyman 2500 tumbler and the die, and component storage.
Preferably build a noise reduction closet (insulate walls) and put your tumblers in that. Tumbers MUST have their plugs connected to a switch/built-in timer so that flipping the switch automatically sets the timer for your previously set time.
If I had everything I want, I would pipe PVC under my bench connected to a shop vac......with outlets in a couple of places (vac of course would be in the NR closet above), and a switch to it in a handy place I can reach working at my bench.
Best lighting is LED can lights every 2' above your benches. Florescents are ok, but leds are less hassle when it come time to change bulbs.....or worse, ballasts. Plus unlike florescent lighting, you don't have to worry about having LEDs too close to your electronic scales.
Oh, and make a place for a vice, and a drill press is a handy feature.